1. Technical Field
The present invention relates to a concentrating lens of a light emitting diode (LED) lamp.
2. Description of the Prior Art(s)
As an LED is high in luminous efficiency, durable in service life, and has no toxic substances, the LED lamp replaces the conventional fluorescent lamp to be the light source of the light box.
With reference to FIGS. 9 to 12, to project the light emitted from an LED 70 to the two opposite side walls 61 of the light box 60, the LED lamp comprises a concentrating lens 50. The concentrating lens 50 comprises a top 51, a bottom 52, a light output surface 53 disposed on the top 51, a light input surface 54 disposed on the bottom 52, and a recess 55. The light input surface 54 comprises a convex plane 541 and a surrounding plane 542 connected with the convex plane 541. The recess 55 is formed concavely on the bottom 52 and towards the top 51. The recess 55 is surrounded by the light input surface 54. The recess 55 comprises a bottom opening 551 surrounded by the surrounding plane 542.
As shown in FIGS. 9, and 11 to 13, the LED 70 and the concentrating lens 50 are mounted on an end wall of the light box 60. The LED 70 faces the light input surface 54. After the light emitted by the LED 70 enters the concentrating lens 50 via the light input surface 54, the light departs from the concentrating lens 50 via the light output surface 55 and is distributed on the side walls 61 of the light box 60 for lighting up the light box 60.
However, the concentrating lens 50 concentrates the light emitted by the LED 70 only to the position on each of the side walls 61 distal from the LED 70. The concentrating lens 50 hardly distributes the light to the position on each of the side walls 61 close to the LED 70. Therefore, the concentrating lens 50 is incapable of allowing the light emitted from the LED 70 to light up the light box 60 uniformly.
To overcome the shortcomings, the present invention provides a concentrating lens of a light emitting diode lamp to mitigate or obviate the aforementioned problems.